Panelboards are electrical power distribution devices, typically mounted in enclosures, that provide electrical power, overcurrent protection, short circuit protection and/or disconnecting means (circuit switching) to multiple load circuits. Multiple conductors within the panelboard, having different instantaneous voltage potentials (e.g., A, B, and C phases), are used to power these circuits through device connection points (e.g., circuit breaker mounting locations) distributed at multiple locations throughout the interior of the panelboard.
A typical panelboard assembly can have as many as three main power conductors (e.g., A, B and C phases), with or without an additional main neutral conductor, all operating at different instantaneous voltages. Multiple individual load circuits (e.g., branch circuits) can be established by electrically connecting an external load to these internal conductors through, for example, circuit breakers mounted to the panelboard. If desired, a single panelboard assembly can provide loads at different voltage values (e.g., 110V or 220V) depending on which combination of internal conductors are used to supply a circuit.
In addition to distributing power to multiple external loads, panelboards and their accompanying components may provide overcurrent and/or short circuit protection for the branch circuits. This protection may be achieved by the use of overcurrent protection devices (circuit breakers such as single pole breakers, two pole breakers, GFIs, AFCIs, CAFCIs, switches, or fuses) installed in the panelboard for each branch circuit.
Under short circuit conditions, the electrical impedance on an external load is reduced to a very low value, thus allowing the flow of current many times higher than intended for the branch circuit. An important effect of these extremely high current levels is the creation of intense magnetic fields that may cause very high attractive and repulsive magnetic forces between the various conductors within the circuit and also within the panelboard. These forces can be on the order of hundreds of times greater than the weights of the effected conductor components. These large forces can produce large structural stresses, possibly leading to damage to the panelboard assembly. Thus, depending on the rating of the panelboard assembly, the number of overcurrent protection devices that the panelboard assembly is designed to accommodate, and the various sizes of the bus bars (e.g., length, width, and thickness) due to ratings and material choice, many different panelboard assembly designs have been developed.
Thus, existing panelboards, although adequate for their intended purpose, include designs that are quite divergent from each other because of the different design criteria. This necessitates expensive tooling, expensive inventory of multiple components, and the like for their manufacture.
Therefore, there is a need for improvements to panelboard designs for electrical distribution to make them more cost effective.